Nuon Chea is 88 years old. Khieu Samphan is 84. They are the most senior surviving officials of the Khmer Rouge, the regime that ruled Cambodia from 1975 to 1979 and is responsible for the deaths of up to two million Cambodians. Both men have already been tried, found guilty of crimes against humanity, and sentenced to life imprisonment (those sentences are currently being appealed).

So why is the Extraordinary Chambers in the Courts of Cambodia (or ECCC, the tribunal jointly established by the UN and government of Cambodia) trying them again, for a second set of crimes? Why is a court that has spent over $200 million to find three people guilty actually holding a second trial for two of those people, who have already received a life sentence?

The answer lies in the quest for accountability, historical reckoning, reconciliation, and the need to provide justice for victims and survivors of the Khmer Rouge.

This week, 35 years after the fall of the Khmer Rouge, the evidence phase of the second trial against Khieu Samphan and Nuon Chea begins. Because of the advanced age and health problems of the two defendants, the charges against them were divided into two cases. The first case (known as Case 002/01) was relatively narrow in focus, concentrating on the evacuation of Phnom Penh and other cities and the execution of soldiers and others loyal to the former regime. The second trial (Case 002/02), which begins with opening statements on October 17, is much more expansive and arguably addresses the most dire of the Khmer Rouge’s crimes. It will cover charges of genocide against Cham Muslims and Vietnamese; forced marriages and rape, torture, and executions at security centers; internal purges of the regime; and torture, murder, and abuses committed at forced worksites and cooperatives.  For many Cambodians, these are the crimes that defined the regime and affected them and their loved ones personally.

Khmer Rouge atrocities rank high on the appalling (and long) list of inhumanities committed in the last century, and the Case 002/02 trial is therefore one of the most significant since the Nuremburg trials following World War II. Even long-delayed accountability is important to Cambodians, too many of whom still live in conditions of extreme poverty and deprivation likely linked to their cruel history. The trial contributes to the historical record: for most of the children of Khmer Rouge victims, often deprived of education or information about the regime, the trials reveal what their families and their country suffered. (A forthcoming Open Society Justice Initiative report will look at the impact of the ECCC in Cambodia.) The trial is also notice to the rest of the world that victims of mass crimes deserve and need justice.

Evidence related to the Khmer Rouge and the roles of Nuon Chea and Khieu Samphan in the regime was covered in the first trial and can be efficiently admitted into the second trial without the need for repetition. This will allow the Trial Chamber to focus on more detailed evidence of the specific crimes alleged and should make for a trial that provides Cambodians with added understanding of Khmer Rouge actions, as well as a broader sense of accountability than existed after the first trial of Nuon Chea and Khieu Samphan. The government of Cambodia could greatly magnify the trial’s impact—and demonstrate a commitment to accountability—by ensuring that the proceedings are televised (the government exercises extensive control over television broadcasting).

Given the fragile health of the accused, beginning this second phase trial without delay is a critical step and should be quietly applauded. More raucous applause should be withheld until we see if the court pursues additional crimes alleged in Cases 003 and 004.

The ECCC, flawed and troubled in numerous respects, has exceeded the expectations of many, with two judgments delivered against three accused and now the beginning of this second trial against Khieu Samphan and Nuon Chea. Many skeptics never expected to see a conclusion of the first trial against these accused, and were not convinced that donors to the court, including the government of Cambodia, would continue to provide funds or diplomatic support for a second trial. While neither the court nor those interested in its success can ignore the need for it to address critical issues of independence, fairness, outreach, and funding, it is appropriate to recognize that the court has overcome huge hurdles and proven itself capable and resilient in beginning this trial to address core crimes of the Khmer Rouge regime.

Some doubters may feel that holding a second trial for men who have already received life sentences is wasteful and unnecessary. But if the ECCC is to fulfill its mandate, Case 002/02 is needed to increase understanding of the Khmer Rouge period and provide accountability for the mass crimes that affected millions of Cambodians. The trial’s opening is a good place to start.